The main objective of this investigation is to develop a protocol for examining the relations among psychological factors, adherence to physical therapy regimens, and recovery progress in the rehabilitation of sport- related orthopedic injuries. Preliminary research in sports medicine settings has shown that psychological factors such as self- motivation, perceived social support, and belief in the efficacy of the rehabilitation regimen are related to rehabilitation adherence. These preliminary studies, however, have not included measures of recovery progress and either have been retrospective or have not controlled for injury type. The purpose of this study will be to examine prospectively the relations among psychological factors, rehabilitation adherence, and short-term postsurgical recovery progress for a single type of sport-related orthopedic injury. Patients with acute anterior cruciate ligament tears will be administered a battery of questionnaires (measuring psychological variables such as self-motivation, perceived social support, and psychological distress) immediately prior to reconstructive surgery. Measures of adherence to the rehabilitation regimen will be obtained on a session-by-session basis following reconstructive surgery. Patients will report on their completion of home rehabilitation exercises and their physical therapist/athletic trainer will indicate the patients' attendance and intensity of completion of prescribed exercises. Objective measures of recovery progress will be taken at five months postsurgery. Data collected in this study will afford a preliminary evaluation of the extent to which psychological factors are related to adherence and recovery progress in the rehabilitation of sport-related orthopedic injuries. This study would facilitate the piloting of procedures for more extensive longitudinal research in this area. It is hoped that this line of research will eventually allow for the development of behavioral interventions to increase rehabilitation adherence and to expedite recovery from sport-related orthopedic injuries.